The modest one-liners of the dangers of smoking, now featured on cigarette packs, may soon turn into gory images and messages that will cover nearly half the pack.

The U.S. Food and Drug Administration unveiled 36 jarring labels Wednesday aimed at escalating efforts to warn smokers of the fatal consequences of cigarette smoking. These labels represent the agency's exercise of its new authority over tobacco products and the most significant change in cigarette warnings since companies were forced to add the mandatory Surgeon General's warning in 1965.

Some of the proposed images include a man smoking from a tracheotomy hole, a cadaver labeled to show it died from lung disease, and a pained infant exposed to smoke.

For decades federal regulators and health experts have warned that cigarettes are deadly. But Matthew L. Myers, president of the Campaign for Tobacco-Free Kids, called the ramped-up measures "a timely and much-needed shot in the arm."

"The current warnings are more than 25 years old, go unnoticed on the side of cigarette packs and fail to effectively communicate the serious health risks of smoking," said Myers.

Although smoking rates have declined overall since the 1960s, health officials noted that rates have leveled off in the last decade. About 21 percent of U.S. adults, and nearly 20 percent of high school students smoke cigarettes, according to the Centers for Disease Control and Prevention.

The agency's goal is to reduce the 443,000 deaths associated with tobacco use each year.

Previous studies suggest that graphic health warnings displayed in other countries worked better than text warnings to motivate smokers to quit, and nonsmokers not to start.

The U.S. was the first country to require health warnings on tobacco products. But it is now playing catch up to more than 30 countries that already require large, graphic cigarette warnings.

Images used on cigarette packs in countries like Canada are so disturbing that some smokers buy covers for their cigarette packs to block out the images.

"Having a coordinated policy, having these warnings, making them so visible, making them real is, in my opinion and in the opinion of the American Cancer Society, going to be a very positive step forward," said Dr. Len Lichtenfeld, deputy chief medical officer for the American Cancer Society.

Experts Say Fear Messages May Not Work for Long

But some experts wonder how long the proposed fear messages will work.

"The point of putting these pictures is the shock value, and research tells us shock value on its own rarely works," said Timothy Edgar, associate professor and graduate program director of health communication at Emerson College in Boston, Mass.

Most Americans already know that smoking is dangerous -- the message that the FDA is trying to convey, said Edgar. And while the campaign may dissuade some smokers at the start of the campaign, the communication tactic may not spur many to kick the habit for good, if at all.

"I think people are still going to have a hard time saying, yes that's me on that label," said Edgar. "There's a physical addiction involved in this as well. It's not an absolute choice for many who smoke."